As the fall equinox arrives in Philly, nights are about to get brighter and days more colorful

These days it’s as though the sun can’t wait to call it a day. The sunrise-sunset period has been shrinking by more than 2½ minutes daily, the avaricious darkness nibbling at both ends of the day.

The instant of the autumnal equinox occurs at 2:19 p.m. Monday in Philadelphia — when the sun will be lasering its most direct light on the equator. Later it will sink beneath the horizon before 7 p.m. for the first time since March 8.

But as the astronomical fall arrives, things are about to get brighter, at least at night, with three consecutive supermoons flooding the region with moonlight on multiple nights, if the skies cooperate.

Plus, the rate of nighttime creep soon will slow approaching the winter solstice.

The daytime skies are becoming ever more interesting for the region’s bird-watchers. And things are about to become more colorful as the already-turning leaves take on the tints of apples and pumpkins.

The moon will be hiding in its “new” phase as the Earth directly faces its dark side at the start of the week. But it will become gradually more visible the next two weeks as it approaches its “full” phase, which matures on Oct. 6. It also will be making one of its closer approaches of the year, qualifying as a “supermoon,” and will appear about 30% brighter than it does when it’s farthest away.

The same will be true for the full moons of Nov. 5 and Dec. 4.

And these aren’t just one-night affairs. The moon will be at 90% or more of fullness for six days in October, five in November, and six again in December.

The October version will be casting its silvery glow on the early-turning leaves, and, in November, on whatever is left of them. By December, the trees should be mostly bare, so on clear nights the shadows of their trunks and nerve-ending branches should be dramatic.

According to the experts who monitor the progress of the foliage season, for the intensity of leaf color this is the stretch run in terms of the weather, and it couldn’t be much better.

“If you have a preponderance of sunny conditions starting in the first or second week of September, and continuing into October, then you will have more brilliant fall leaf colors,” said Howard S. Neufeld, a biology professor at Appalachian State University. That’s in the Blue Ridge Mountains, where the foliage tourism season is very serious business.

To date, this month has had only a handful of cloudy days in Philadelphia, and the outlook for the next several days is calling for sun and temperatures about where they should be this time of year.

Ryan Reed, author of the weekly updates published by Pennsylvania Department of Conservation and Natural Resources, expects the colors to come on earlier than usual. The updates — these are based on actual field reports from foresters, not tourism types — were scheduled to begin Oct. 2, but he has moved up the start date to Thursday.

The show should peak in the Philly region around Halloween into the first week of November.

Whatever the leaves decide, it won’t affect the birds’ plans, and the southbound traffic overhead is about to pick up.

The great migrations peak the last week of September into the first week of October, says Keith Russell, an ornithologist with Audubon Pennsylvania.

More species of birds appear in the skies over the Philly region the last week of September and the first week of October than at any other time of the year, said Russell, Audubon’s program manager for urban conservation. “So it’s a great time to go birding.”

Taking center stage among the avian visitors are the chimney swifts (nothing to do with Taylor) and the broad-winged hawks, which can appear in tremendous numbers with thousands visible in a single day, Russell said.

The swifts, on their way to the Amazon with no help needed from Google Maps, swarm by the hundreds and thousands. And they do very much hang out in chimneys.

On Monday night, an annual chimney swift watch will be held at the site of the former Hallahan High School in Center City (now the site of Belmont Charter High School), where the swifts have been known to congregate. Over 10,000 were reported there two years ago.

The migrating broad-winged hawks also show up in groups of thousands at places such as Rose Tree Park, in Upper Providence, Delaware County, and Militia Hill, in Fort Washington, Montgomery County.

For more information about the hawks and swifts and where to see them, contact the Delaware Valley Ornithology Club.

The peak of the 11-year “sunspot” cycle shows signs of backing off, and those solar storms that have ignited the aurora may be occurring less frequently.

That said, various research has shown that the weeks around the equinoxes are favorable for the aurora, notes the astronomy journal EarthSky. That has to do with the alignment of the magnetic fields of the Earth and sun. They did appear over Philly last October, albeit briefly.

However, under any circumstances, seeing the northern lights at Philly’s latitude is among the longest of long shots.

Aurora or not, you can count on amazing sunsets as the sunlight becomes ever more oblique. Check out what it does to the foliage and its remnants in the treetops, and you’ll see why naturalist Edwin Way Teale called autumn “the glorious flaming sunset of the year.”